Screw driver



Patented Mar. 13, I923.

NEFE S EAT- sans ears.

scanw DRIvER.

Application filed May 2, 1921. Serial No. 466,109.

lowing is a specification, reference being had to the accompanying drawing.

My invention relates to screw drivers, and its object is to obviate entirely, the possibility of slipping of such tools while in use.

This desideratum I attain by so shaping the tip of the driver as to afford free lateral edges and comparatively sharp corner nibs which are adapted to engage the side walls of screw slots at the very bottom of the;

latter.

One advantage of my invention is that screw drivers of standard types may be ren dered slip proof without necessitating any changes whatever in their construction other than the shaping above referred to.

Other advantages of my invention will become readily apparent from the detailed description which follows. I

In the drawing, Fig. I is an elevation of a screw driver conveniently embodying'my invention.

Fig. II is a fragmentary view of the shank of the driver as viewed from the left of Fig. I. a v

Fig. III is an end view of the shank of the screw driver. j

Generally speaking, the screw driver shown in Fig. I is of a typical or well known form, in that it comprises a handle 1 and an integral shank 2 whose end. is somewhat broadened and provided with flattened sides 40 3-3 which are relatively inclined, as best seen in Fig. II, to lend the desired taper in affording a driver blade.

In carrying out my invention, the flattened sides 3-3 of the blade are gouged to- Ward opposite corners of the driver tip, as indicated at 4- 1. The free edges 5, thus produced at each side of the driver tip, ex-

tend across substantially the-full Width of the blade, and in the act of driving a screw, bear only against the side walls of the screw slot at the very bottom of the latter, thus obviating to a great extent the possibility of slipping.

' Moreover, it is to be particularly noted that the character of the gouging is such that the opposite corners of the driver tip are rendered comparatively sharp so that they may dig into the side walls'of the screw slots and thus render the engagement between the driver and the screw even more 6 positive to the advantage that the efliciency of the toolis thereby correspondingly enhanced. It is also important to note from Fig. III that the gougings 4-4 are so disposed that the driver blade is not unduly weakened. 5

A screw driver such as herein disclosed will obviously be non-slipping only in the course of driving screws. This capacity is all that is ordinarily necessary, since withdrawal of screws is comparatively much easier of accomplishment and may be effected in the usual way. If a driver for withdrawing screws should be found desirable, this may be had by simply reversing the relative locations of the gougings on opposite sides of the driver blade.

WVhile I have shown and described my invention as particularly useful in connection With hand screw drivers, it is, of course, ob- 0 vious that the'same may be employed, with equal advantages, in connection with screw driver bits such as used in braces or automatic screw driving machines.

. Having thus described my invention, I

claim A screw driver comprising a blade'having each of its flat sides formed adjacent the bit with a transverse concave groove entering the edge of the blade and which is widest at the point of entrance and the rim edges of which curve in converging relation, the grooves being each of a length to extend beyond the axial center of the blade so as to afford ample turning clearance for the blade without engaging the upper edges of the kerf walls a screw.

In testimony whereof, I have hereunto signed my name at Philadelphia, Pennsyl- Vania, this 28th. day of April 1921.

ARTHUR R. EARNSHAW.

' "Witnesses:

JAMES H. BELL, E. L. FULLERTON. 

